Node Trees: A model for configuring and managing large distributed systems (by alaric)

(FX: Flashback wibbly wobbly transition...)

So, as a teenager, I started working on ARGON, a distributed operating system. At the time, the CPU cost of encrypting traffic could be a significant matter when communicating over untrusted networks, so I'd worked out a protocol whereby network communications between clusters could negotiate to find the lowest-cost encryption scheme that both parties considered acceptable for the sensitivity of the data being transmitted: more sensitive data would require more secure protocols, which presumably excluded cheaper ones.

But I wanted to do something similar for communications within a cluster; I started with the same idea - finding the cheapest algorithm considered secure enough for the communication at hand. This could be simplified, as all nodes within a cluster share the same configuration, so both will agree on the same list of encryption systems, with the same security and costliness scores; so no negotiation is required - the sender can work out what algorithm to use, and be confident that the recipient will come to the same conclusion.

However, it pained me that highly sensitive data would be encrypted with expensive algorithms, even between machines connected by a trusted network - maybe even right next to each other, connected by a dedicated cable. I wanted a way to be able to, through configuration, tell the cluster that certain links between nodes in the cluster are trusted up to a certain level of sensitivity. Connections at that sensitivity level or below can use those links without needing encryption; anything above would use a suitably trusted algorithm.

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A draft specification for IRIDIUM (by alaric)

As discussed in my previous post, I think it's lame that we use TCP for everything and think we could do much better!. Here's my concrete proposal for IRIDIUM, a protocol that I think could be a great improvement:

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Debugging poor home wifi at the Snell-Pym residence (by alaric)

So, we have a fairly complicated network at home - the Snell-Pym Family Mainframe has a dedicated DSL link with a static IP for hosting various Internet-facing things, as well as providing internal services to the home LAN. The home LAN has the usual mix of desktop computers, the laser printer, and two wireless APs for mobile devices to connect to - one in the house and one in the workshop, because one can't get a good signal to both locations. And there's a separate infrastructure LAN for systems control and monitoring.

Now, we've often had on-and-off poor connectivity on the wifi in the house; this used to happen sporadically, usually for around a day, then just get better. The wifi signal strength would remain good, but packet loss was high (10-20%) so stuff just didn't work very well. TCP is poor at high packet loss; it's OK once a connection is open, but packet loss during the initial SYN/SYNACK/ACK handshake causes it to take a long time to retry on most implementations.

I went looking for interfering networks (we live in a pretty wifi-dense urban area) using an app called "Wifi Analyzer" on my Android phone, and it showed a strange network, always on the same channel as the house wifi (as in, if I changed the channel, it would move too). The network never had a name, and the signal strength was about the same as the house wifi; sometimes a bit stronger, sometimes a bit weaker. Read more »

Insomnia (by alaric)

There's something about the combination of having spent many weeks in a row without more than the odd half-hour here and there to myself (time when I get to do whatever I like, rather than merely choosing which of the list of things I need to get done urgently I will do next, or just having no choice at all), and knowing I need to get up even earlier the next morning than usual (to dive straight into a long day of scheduled activities), that makes it very, very, hard for me to sleep.

So, although I got to bed in good time for somebody who has to wake up at six o'clock, I have given up laying there staring at the ceiling, and come down to eat some more food (I get the munchies past midnight), read my book without disturbing Sarah with my bedside light, and potter on my laptop. I need to be up in five hours, so hopefully emptying my brain of whirling thoughts will enable me to sleep.

There's lots of things I want to do. Even though it's something I need to get done by a deadline, I'm actually enthusiastic about continuing the project I was working on today; making an enclosure for our chickens. This is necessary for us to be able to go away from the house for more than one night, which is something we want to do over Christmas; thus the deadline.

Three of the edges of the enclosure will be built onto existing walls or woodwork, but one of them needs to cut across some ground, so I've dug a trench across said bit of ground, laid an old concrete lintel and some concrete blocks in the trench after levelling the base with ballast, and then mixed and rammed concrete around them. When I next get to work on it, I'll mix up a large batch of concrete and use it to level the surface neatly (and then ram any left-overs into remaining gaps) to just below the level of the soil, then lay a row of engineering bricks (frog down) on a mortar bed on top of that in order to make a foundation that I can screw a wooden batten to. With that done, and some battens screwed into the tops of existing walls that don't already have woodwork on, I'll be able to build the frame of the enclosure (including a door), then attach fox-proof mesh to it, and our chickens will have a new home they can run around in safely.

Thinking about how I'm going to lay the next batch of concrete in a nice level run, working around the fact that I only have a short spirit level by placing a long piece of wood in there and levelling it with wedges and then using it as a reference to level the concrete to, has been one of the things running around in my head this evening.

Another has been the next steps from last Friday, when I had a fascinating meeting with a bunch of interesting people in the information security world. You see, I've always been interested in the foundation technologies upon which we build software, such as storage management, distributed computing, parallel computing, programming languages, operating systems, standard libraries, fault tolerance, and security. I was lucky enough to find a way into the world of database development a few years ago, which (with a move to a company that produces software to run SQL queries across a cluster) has broadened to cover storage management, distribution, parallelism, AND programming languages. So imagine my delight when said company starts to develop the security features in the product, and I can get involved in that; and even more when (through old contacts) I'm invited to the inaugural meeting of a prestigious group of peopled interested in security. That landed me an invite to the second meeting (chaired by an actual Lord, and held in the House of Lords!), the highlight of which was of course getting to talk to the participants after the presentations. I found out about the Global Identity Foundation, who are working pn standardising the kind of pseudonymous identity framework I have previous pined for; I'm going to see if I can find a way to get more involved in that. But I need to do a lot of reading-up on the organisations and people involved in this stuff, and figuring out how I can contribute to it with my time and money restrictions.

I'd really like to have some quiet time to work on my secret fiction project, too. And I want to investigate Ugarit bugs. Some bugs in the Chicken Scheme system have been found and fixed lately, so I need to re-test all these bugs to see if any of the more mysterious ones were artefacts of that. I'm in a bit of a vicious circle with that; the longer it is since I've been tinkering with the Ugarit internals, the longer it'll take me to get back into it, and the more nervous I feel about doing so. I think I might need to pick off some lighter bit of work with good rewards (adding a new feature, say) and handle that first, to get back into the swing of things. Either way, I'll need a good solid day to dig into it all again; trying to assemble that from sporadic hours just won't cut it.

I'm still mulling over issues in the design of ARGON. Right now I'm reading a book on handling updates to logical databases - adding new facts to them, and handling the conflicts when the new facts contradict older ones, in order to produce a new state of the database where the new fact is now true, but no contradictions remain. I need to work this out to settle on a final semantics for CARBON, which will be required to implement distributed storage of knowledge within TUNGSTEN. I need a semantics that can converge towards a consensus on the final state of the system, despite interruptions in internal network connectivity within the cluster causing updates to arrive in different orders in different places; doing that efficiently is, well, easier said than done.

I really want to finish rebuilding my furnace, which I hoped to get done this Summer, but I'm still assembling the structural supports for it. I've made a mould to cast shaped refractory bricks for the lining of the furnace, but I've yet to mix up the heatproof insulating material the bricks need to be made out of and start casting the bricks, as I still need to work out how I'll form the tuyere.

I want to get Ethernet cabled to my workshop, because currently I don't have a proper place for working on my laptop; I have to do it on the sofa in the lounge to be within range of the wifi, which isn't very ergonomic, doesn't give me access to my external screens, and is prone to interruption by children. I find it very motivating to be in "my space", too; the computer desk in the workshop is all set up the way I like it. And just for fun, I'd like to rig the workshop with computer-controlled sensors and gizmos (that kind of thing is a childhood dream of mine...).

This past year, I've tried booking two weekend days a month for my projects, in our shared calendar. This worked well at the start of the year, with projects such as the workshop ladder and eaves proceeding well, but it started to falter around the Summer when we got really busy with festivals and the like. I started having to fit half-days in around other things, which meant spending too much time getting started and clearing up compared to actually getting things done, so my morale faltered; and with so much other stuff on, I've been increasingly inclined to spend my free time just relaxing rather than getting anything done. On a couple of occasions I've tried taking a week off work to pursue my projects, but I then feel guilty about it and start allocating days to spending more time with the children or tidying the house, and before I know it, five days off becomes one day of actual project work. I need to stop feeling guilty about taking time to do the things I enjoy, because if I don't, I'll be too tired and miserable to do a good job of the things I should be doing! And rather than booking my monthly project days around other stuff that's going on, next year I'm going to mark out my two days each month in advance, and then move them elsewhere in the month if Sarah needs me to do something on that particular day, to decrease the chance of ending up having to scrape together half-days around the month (or to skip project days entirely, as I ended up doing last month). I feel awful about saying I'm going to spend days doing what I feel like doing rather than the things the rest of my family need me to drive them to, but if I don't, I think I'm going to fall apart!

Now... off and on I've spent forty minutes writing this blog post. So with my whirling thoughts dumped out, I'm going to go back to bed and see if I can sleep this time around. Wish me luck!

Is information security good? (by alaric)

One of the interesting things to have come from Edward Snowden's leaks of classified documents is that the American National Security Agency has been working to introduce flaws into the design and implementation of security technologies, in order to make it easier for them to break said security for their own ends.

There's been a lot of outrage about that. The argument for it is that the ready availability of strong security technology makes it easier for bad folks to conceal their crimes (and, worse, conceal the fact that they are planning such crimes, so they cannot be stopped in advance), so the NSA is right in acting to make sure people don't have strong security technology. However, even if we can trust the NSA (and that is far from certain) such vulnerabilities can be found by people we certainly can't trust: "cyber-criminals" intent on stealing our credit card details in order to rob us of our money, commercial competitors looking for strategic advantage, and so on.

There are also deeper issues that have been raised; this means that the NSA is covertly working to sabotage the products of US companies. Should they be allowed to do that? Can those companies now sue them for damages?

But I think that, at the heart of the debate over this, is an even deeper issue.

We have the NSA - the part of the US government officially responsible for information security - acting to subvert the information security available to US individuals and companies, on the grounds that it is harmful to the public if they have strong security. While on the other hand, we have individuals and companies striving for better security; working to make more secure products, choosing products that claim to provide security benefits, and so on.

This shows, to me, that there's a big unresolved question that US society as a whole - government and non-government together - needs to ask themselves: Is information security good? The government's official position seems to be that information security is harmful, as it makes it harder to provide a more general notion of security that is threatened by criminals, foreign governments, and terrorists; while everyone else's position seems to be that information security is good because they don't want information criminals and foreign governments stealing their secrets (terrorists don't seem to have cottoned to this trick yet) - and, maybe, because they don't want the government knowing ("stealing" is a contentious term here, as the government gets to define what "stealing" is) their secrets, too.

So before they can really debate whether the NSA's actions are justified or not, I think the US needs to step back and look at the bigger question: Should information security be a right, or not? If not, then they should just use legislation to stop companies and people from wasting resources trying to achieve it while other resources are being spent subverting it so they only receive an illusion thereof. That's just plain inefficient. And if information security is deemed good, then the NSA should be prevented from subverting it, and refocus its efforts on ways of doing its job without being able to break encryption; traffic analysis, meta-data analysis, exploiting specific installations of security systems where a threat is suspected, and so on are all time-honoured mechanisms that work even against well-educated adversaries that use encryption systems that the NSA hasn't been able to subvert.